It can be drunk by itself or made into a drink combining different herbal teas, protein sources, coffee, that has immune strengthening properties to it. The out black layer is bitter and has anti-cancer properties about it. The inner layer has immune strengthening properties about it and is sweet. The inner layer is the part to boil for a sweet liquid that tastes similar to vanilla.
Medical studies have been done on the effect of chaga.
Here is one of a substantial number found on pubmed.
Chaga can be found anywhere where there is birch trees.
Last month I set off to Soyo Mountain near the DMZ to find some chaga.